Strange Signal Problem

Hi All,

I’ve ran into some weird signal issues with a small sytem I work on.

It is a 900MHz system, with 1 AP and 2 SMs, all connectorized.

AP has a 9dB omni antenna, remotes have 10db yagi and 14db yagi antennae respectively.

Each of the remotes have a signal in the -76 to -83dBm range, with jitters anywhere from 2-10. Everything running 7.3.6.

The ap indicates that it is receiving from both @ -67 to -70dBm. The one SM I was working on yesterday took forever to register (5+ mins). Once registered, the link tests were brutal 30%downlink and 60%uplink.

Can anyone explain the signal descrepencies?
Is it possible the AP has bad transmitter?
There is a lot of 900MHz hopping SCADA in the area.

Thanks a lot.


do a spectrum analyzer to find the noise floor & keep in mind you want to keep 10dB below the noise floor. -83dB is a very marginal signal in my part of the world. we do not allow new installations with this weak of a signal. imo thats why the link efficiencies suck.

might want to try 17dB yagi, we’ve had great luck with ours.

The SM has some local interference. Could be another RF source, or fresnel zone intrusion.

Turn off the AP, then run the spectrum analyzer on the SM.

If there is noise, look for the quietest frequency and note it. Then look at the spectrum analyzer on the other SM and AP (Config AP as SM and reboot) to determine this frequency is quiet at both locations. Change the AP to that frequency.

If all frequencies are quiet, then I could start looking at the signal path for a physical obstruction; shooting over a building, tree tops, etc.

my tower is between 2 other WISPs 1mile to the west is on 906 im on 915 then 1 mile to the east is on 916 all our radios are perfectly syncd exept the one on 906 has older firmware so he region is set to other instead of USA and we all seem to be interfering with eachother any ideas would be awsome im thinking 916 and 915 are to close but i need proof for the higher ups thanks

hopefully your all using canopy. if thats the case, time syncing would help you all co-exist

906, 915, and 924 are the non-overlapping frequencies.

With Canopy everything needs to be perfect - sync source, radio configurations, software/hardware mode, etc. ANY variation will result in sub-optimal performance, and the more variation, the more significant the impact.

doesnt matter if everything else is perfect. if 3 are sync’d and 1 isnt thats probably your interference source. probably a stupid question, but did you happen to check each location for 900 mhz phones/baby monitors? ive had a time or two where they are 100% the source. just a thought

yes we did cheack for 900Mhz phones found a few and replaced with 6.0 digital phones and yes we are all using 900mhz canopy i will try 924 but about 8miles away i have a 924 sector ap pointing right at it will that effect me sens its under 10miles away? and by same software do you mean same firmware? coz i am using 8.2.7 thay are using the 7x firmware
thanks for the help

Assuming both of your AP’s are on the same SW, and configured identically including sync source then you should be able to run both on 924. the Canopy design calls for AP’s face-to-face and back-to-back to be on the same freq.

Your guy on 7.x is going to continue to cause you problems, especially as you both add users. See if you can have him update to 8.2.7, add GPS, and configure his AP with the same setting as you.

I can guarantee if he is affecting you, you are affecting him.

GPS, and his AP Have the same setting as me.
i dont know if i can talk him into using the same firmware sens evryone says 7x is beter then 8x but i will try and thanks for the help if you have any other ideas let me know coz im in need of much help lol thanks agean

okay… so i switched my radio to SM mode saw 923 and 924 were opean so i switched it to 924 work’t grate for about a day now im haveing truble agean did a nather scan and now all the channels are takin i am starting to think some one is messing with us i want to shut off all the AP’s
and do a spectrum scan of the town but 1 am 1 of 2 employes and i dont know how to talk the other ISPs into shutiong off there eqip for a few hours …my tower is by a EMS station and a truck stop
but im told EMS is on 800Mhz and trucks are in the lower 80Hz
any more ideas would be awsome thanks

you also have the option of changing polarity on your antennas. where im at, vertical pol is saturated with telemetry data and other wisp’s. just another thought